1. Field of the Invention
The present invention generally relates to a system for coating substrates. More specifically, the invention relates to a plasma coating system and method whereby the introduction of reagents is controlled to enhance the coating formed on the substrate.
2. Related Technology
Generally, plasma coating systems, to which the present invention is applicable, include various stations or zones connected in sequence and through which substrates are moved in a continuous series. These zones may include a load lock, a heating zone, one or more coating zones and an exit lock. In the coating zone(s) is one or more plasma sources, such as an expanding thermal plasma (ETP) source, and associated means for injecting coating reagents. During the coating process, the substrates are moved past the plasma source(s) as a coating reagent(s) is injected into a plasma jet issuing from the plasma source. As the substrates are moved through the resulting plasma plume, a coating is deposited on the surfaces of the substrates.
Such prior art systems do not allow for the simultaneous application of multiple coating sub-layers on to a single side of a substrate. If multiple coating sub-layers are to be applied, the once coated substrate is passed through additional coating zones, where the additional coating sub-layers are applied.